Problem: Solve for $a$ : $25 + a = 6$
Answer: Subtract $25$ from both sides: $ \begin{eqnarray} \\ 25 + a &=& 6 \\ \\ {-25} && {-25} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{25 + a} &\hphantom{=}& \hphantom{6} \\ a &=& 6 {- 25} \\ \end{eqnarray} $ Simplify. $ a = -19$